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i <br />December 1, 1994 '~E~E'~E~ <br />DEC 01 ~gg¢ <br />Ms. Christine Johnston <br />Environmental Protection Specialist Division Ot M• <br />Colorado Division of Minerals and Geology ~Iera15 $ Geolp9Y <br />1313 Sherman, Room 215 <br />Denver, CO 80203 <br />Subject: October 17, 1494 Adequacy Response Letter, Minor Revision No. 138, West Elk Mine, Permit <br />C-SO-007 <br />Dear Ms. Johnston <br />Greystone has been asked to respond to the October 17, 1994 Adequacy Response letter for Minor Revision <br />138. Answers to your questions are listed below in the order in which they were asked. Three copies of the <br />watershed, ditch and culvert runs have been provided for sites within MB-1 and MB2-R. Three copies of all <br />of the hydrology tables and the pond runs for MB2-R and MB-3 are also provided. <br />71te general construction of F_xltibit 66 is evolving in two new directions. Physically, Greystone is providing <br />you with an additional binder, Volume 8A-2, for Exhibit 66 materials. (Please replace the spines of Volume <br />HA with the attached spines of Volume 8A-1). This submittal and future modifications to the watershed, ditch <br />and culvert portions of the plans will be copied single-sided. Hydrologically, the September submittal of the <br />MB-3 as-builts marked a ship away from individual watershed submittals towards hydraulically connected runs. <br />REVISED PERMIT PAGES <br />No response is required. <br />2. As-built drawings for MB-2R and MB-3 were sent From the mine under separate cover. The pond <br />tuns have been revised to reflect the as-built configurations, and are attached. Tables 42 and 45 have <br />been modified accordingly. <br />MB-3 SYSTEM <br />1. A revised SEDCAD+ run has been provided for MB-3 which includes runs for the 10 and 25-year <br />storm. This run is a modification of the previous drainage work, in that null structures replaced the <br />various culverts and ditch descriptions to enable the running of the 25-year storm. In addition, the <br />acreage associated with watershed 15C and the pond itself was incorporated into the run. <br />2. Please delete the individual watershed runs of every watershed in the MB-3 section except 15C and <br />replace it with the existing run which you have. Greystone would like to move towards an exhibit <br />which has drainage runs that follow the water down the watershed to eliminate the burdensome hand- <br />calculations associated with small modifications high in the watershed. At this time, the MB-3 <br />drainage is the only pond in this wnfiguration. <br />3. The orientation of the outfalls of C3-3 and C3-4 will be clarified on Map 54. The outfalls should be <br />located in roughly the same location at the mouth of D3-2A. C3-4 carries the 0.5 cfs From 15E and <br />15L via D3-4B, as set up in the drainage design. Watersheds 15F and 15R discharge into D3-4 and <br />subsequently C3-3. Watersheds 15Q, 15M, 15N and 15D discharge from D3-2A into D3-28 without <br />going through a culvert. <br />5990 Greenwood Plaza Blvd. Suite 250 Englewood, CO 80111 <br />(303) 850-0930 Fax (303) 721-9298 <br />Environmental Planners, Scientists, and Engineers <br />